audio_system.h

#pragma once
 
#include <cstdint>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
 
#include "core/event/bus.h"
#include "core/system.h"
#include "ecs/entity.h"
#include "resource/asset/audio_clip_asset.h"
#include "system/audio/audio_device.h"
#include "system/audio/audio_events.h"
 
namespace Vkm::Engine {
 
class EventBus;
struct AudioSource;

class AudioSystem : public System {
    public:
        AudioSystem() = default;
        ~AudioSystem() override = default;
 
        AudioSystem(const AudioSystem& other) = delete;
        AudioSystem& operator=(const AudioSystem& other) = delete;
 
        AudioSystem(AudioSystem && other) = delete;
        AudioSystem& operator=(AudioSystem && other) = delete;
 
    public:
        void init(FrameContext& ctx) override;
        void update(FrameContext& ctx) override;
        void shutdown() override;

        AudioDevice& device() { return m_device; }

        void setSilent(bool silent = true) { m_silent = silent; }

        VoiceId voiceOf(EntityId entity) const;

        void stopEverything();
 
    private:
        void updateListener(FrameContext& ctx);

        void reconcileSource(
            FrameContext& ctx,
            EntityId entity,
            AudioSource& source,
            const glm::vec3& worldPosition,
            bool simRunning
        );

        void startPendingRequests(FrameContext& ctx);

        void warnIfNoListener(bool spatial);

        void warnIfStereoSpatial(const AudioClipAsset& asset, bool spatial);
 
    private:
        struct ActiveVoice {
            EntityId        entity;
            AudioClipHandle clip;
            VoiceId         voice = 0;
            uint64_t        seenOnFrame = 0;
        };
 
    private:
        AudioDevice m_device;
        bool        m_silent = false;

        std::unordered_map<uint32_t, ActiveVoice> m_voices;

        std::vector<PlaySoundEvent> m_pending;

        std::vector<PlaySoundEvent> m_starting;

        EventBus* m_events = nullptr;

        ListenerId m_playListener = 0;

        uint64_t m_assetEpoch = 0;

        uint64_t m_frame = 0;

        bool m_hasListener = false;
        glm::vec3 m_listenerPosition{0.0f};

        bool m_warnedNoListener = false;

        std::unordered_set<std::string> m_warnedStereoClips;
};
 
} // namespace Vkm::Engine